Method of casting



May 1, 1934- T. A. MILLER ET AL METHOD OF CASTING Filed March 12, 1932 Patented May 1, 1934 PATENT? OFFICE METHOD OF CASTING Theodore A. Miller, Akron, and George T.-

'Williams, Silver Lake Village, Ohio Application March 12, 1932, Serial No. 598,456v

3 Claims.

- This invention relates to methods of casting materials and particularly metals such as aluminum or alloys thereof.

Heretofore in the manufacture of metal articles such as molds for use in vulcanizing rubber it has been necessary first to cast the mold and then to machine the mold to produce the required design therein.

The general purpose of the present invention is to provide a method of casting materials such as aluminum and its alloys whereby the cast product will have a dense, non-porous structure with a smooth surface with any desired design accurately produced therein solely by the casting process. One of the advantages of the process resides in the fact that the finished product is entirely free of voids due to the high pressure to which the molten metal is subjected during the solidification of metal. The resultant product is very dense, has a very low coefiicient of expansion and does not grow from repeated heating and cooling in use.

The foregoing and other purposes of the invention are attained by the method illustrated in the accompanying drawing and described below. It is to be understood that the method is not limited to the specific form thereof shown and described.

Of the accompanying drawing,

Figure l is a sectional plan on line 11 of Figure 2 of equipment for carrying out the invention for making a rubber shoe sole mold, this particular object being selected s'olely forthe purpose of explaining, the invention to those skilled in the art; and

Figure 2 is a section on line 2-2 of Figure l.

lhis case is filed as a continuation in part of the subject matter set forth in our application Serial No. 556,536, filed August 12, 1931, for Method of casting.

Referring to the drawing, the numeral 10 designates a die for a shoe-sole mold which may be supported on a bed plate 11 and may have a cover plate 12 clamped thereon by clamps 13, 13 secured as by screw bolts, 14., 14 threaded into bed plate 11.

The die 10 may be formed with suitable tread 0 designs as indicated at 15 and 16 by suitably extended upwardly about said bore as at 19. The gate 18 provides an opening through which the metal to be cast may be poured into the casting mold formed by the die and cover plate and is also designed to receive a plunger 20 by which pressure may be applied to the metal being cast.

It is not necessary that the gate 18 be employed for filling the mold cavity.

In carrying out the invention, the cover plate 12 is preheated to a temperature sufficiently high to prevent sudden chilling of the metal, the extension 19 being considerably cooler. The chilling of the extension 19 may be secured by radiation only or it may be artificially chilled if desired. The die 10 is also preheated. The molten 7 metal is poured into the assembled equipment through the gate 18 and the plunger 20, which is chilled either by radiation or .artificially, is applied to the opening and subjected to heavy pressure. The cold plunger chills and solidifies a. 76 thin layer of the material being cast as at A which seals the casting mold against leakage of the molten material up about the piston.

Due to the fact that the molten material being cast under heavy pressure will tend to leak 80 through the slightest crack or through the pores of the metal, the casting die and cover plate are preferably made from a dense metalsuch as high silica iron and a. chilling ring S of metal or the like which is not preheated may be placed around the joint between the die and cover plate. The molten material tending to leak through the joint is chilled and congealed by ring S ta seal the joint. Any other means may be employed for chilling the sprue which may be formed where the mold is parted.

The pressure of the plunger is maintained and continued until the casting B has solidified. As the main body of the casting solidifies the plunger, acting upon the chilled slug in the gate, is moved inwardly under high pressure which forces the metal in the neck 19 into the body of the casting, thereby eliminating all voids in the casting during the solidification of the metal, and making a solid, non-porous article of specific gravity higher than metal cast in any-of the usual processes. It is then relieved and the casting removed from the casting mold. It has been found that there is a slight shrinkage to the compressed cast material which necessitates preheating the mold with the contained casting to effect easy removal of the casting.

The resulting casting is smooth and finished having the desired pattern sharply and accurately defined therein. The portion of metal formed in 1110 the bore 18 may be removed from the upper face of the casting by machining and the shoe sole mold is then ready for use.

While the process has been described and shown in connection with the molding of a particular form, 1. e. a shoe sole mold, the process is adaptable for and may be used in casting any variety of objects, the different steps to be employedbeing varied withthe special objects or articles to be cast. It has not been thought necessary to describe the details of the process for special purposes, such details being obvious to those skilled in the art.

What is claimed is:

1. That method of casting metal articles which comprises providing an article mold, with an opening therein, and providing a plunger slidable in said opening, preheating said mold substantially to the temperature of the molten metal to be cast, filling the mold with molten metal in a freely fiowable state, thereafter applying the pressure of said plunger while in a cold state to said metal in the opening while said metal is in a uniformly molten, freely fiowable state, said cold plunger forming a sealing slug of solidified metal in the opening to prevent leakage therefrom, said mold being constructed to prevent flow of the molten material therefrom when under pressure, and maintaining said pressure until said molten metal has solidified in the mold whereby the metal in the resulting article is of uniform density and texture through the entire body thereof.

2. That method of casting metal articles which comprises providing an article mold with an opening therein about which is an extension from the mold and providing a plunger slidable in said opening, preheating said mold substantially to the temperature of the molten metal to be cast and the extension to a somewhat lesser temperature, filling the mold with molten metal in a freely fiowable state, thereafter applying the pressure of said plunger while in a cold state to said metal in the extension while said metal is in a uniformly molten, freely fiowable state, said cold plunger forming a sealing slug of solidified metal in the opening to prevent leakage therefrom, said mold being constructed to prevent flow of the molten material therefrom when under pressure, and maintaining said pressure until said molten metal has solidified in the mold whereby the metal in the resulting article is of uniform density and texture through the entire body thereof.

3. That method of casting metal articles which comprises providing a sectional article mold with an opening therein and providing a plunger slidable insaid opening, preheating said mold substantially to the temperature of the molten metal to be cast, filling the mold with molten metal in a freely fiowable state, thereafter applying the pressure of said plunger while in a cold state to said metal in the opening while said metal is in a uniformly molten, freely fiowable state, said cold plunger forming a sealing slug of solidified metal in the opening to prevent leakage therefrom, and chilling and congealing any metal issuing from between the sections while said molten metal is under pressure to confine the molten metal in the mold whereby a heavy pressure may be maintained, and maintaining said pressure until said molten metal has solidified in the mold whereby the metal in the resulting article is of uniform density and texture through the entire body thereof.

THEODORE A. MILLER. GEQRGE T. WILLIAMS. 

